In semiconductor integrated circuit manufacturing, integrated circuits (ICs) are conventionally tested during manufacturing and prior to shipment to ensure proper operation. Wafer testing is a testing technique commonly used in production testing of wafer-mounted semiconductor ICs where a temporary electrical connection is established between automatic test equipment (ATE) and ICs formed on the wafer to demonstrate proper performance of the ICs. Components used in wafer testing include an ATE test board, a multilayer printed circuit board connected to the ATE which transfers test signals between the ATE and a probe card assembly. Conventional probe card assemblies include a printed circuit board a probe head having a plurality of flexible probing tips attached thereto. In operation, a device under test (DUT) is moved into position so the probing tip makes contact with corresponding contact points on the DUT.
Prior to testing, the probing tips are brought into contact with the DUT. It is important that each of the probing tips have sufficient electrical contact to the corresponding contact pads (or bumps) on the DUT in order to achieve accurate test result. As the number of circuits being tested increases, so do the number of probing tips required for testing and the amount of pressure required to produce the desired electrical contact between the probing tips and the DUT. However, increasing pressure has the undesired effect of warping the probe card, which prevents some probing tips from producing the desired electrical contact. Although attempts have been made to address this issue, there remains room for substantial improvement.